1. Field of the Invention
This invention relates to a system for reproducing a video signal recorded in parallel track sections on a recording medium, and more particularly to a head-position control circuit for a magnetic head scanning a magnetic tape to record or reproduce signals thereon.
Generally, in a VTR (Video Tape Recorder), a magnetic head is mounted at a predetermined position in a rotary head drum assembly. The magnetic head rotates along a predetermined rotary path during recording as the tape moves past it along a helical path. However, it is preferable for various reasons to deflect the magnetic head during its rotation. For example, if tape motion is stopped or slowed for still or slow-motion reproduction, the path of the recording heads across the tape is skewed with respect to the recorded track. This is due to the fact that the recorded track is laid down on a path which includes the motion of the heads plus the motion of the tape. This so-called "tracking error" can be corrected by deflecting the magnetic head in the direction normal to the rotary path so as to align the scanning path of the magnetic head with the recorded track. This permits obtaining of a well produced picture both in the still and the slow-motion mode.
During normal reproduction, the magnetic head can be controlled in the same manner by means of a servo-control. Deflection of the magnetic head in the direction of the rotary path can be employed for adjusting the scanning speed of the magnetic head so as to eliminate any time base error or variation from the reproduced video signal. Deflecting the magnetic head so as to change its direction of the operative gap with respect to the recorded track, is effective to eliminate "cross-talk" between adjacent recorded tracks by utilization of azimuth loss.
2. Description of the Prior Art
Generally, in order to control the position of the magnetic head, the latter is mounted on an electro-mechanical transducer such as a piezo-electric element or a solenoid, and a predetermined drive signal is supplied to the electro-mechanical transducer. The piezo-electric element is capacitive and little electric power is required for driving it. The piezo-electric element requires a high voltage DC drive signal. Rotating joints or connections employing brushes and slip rings have been used to apply the high voltage DC drive signal from the non-rotating part of the apparatus to the rotating member carrying the heads. The brush and the slip ring operate through mechanical sliding contact with each other. Therefore, slip rings and brushes have a short life, provide unstable contact and are a troublesome cause of electrical and/or mechanical noise.